About the development of local area network (LAN) people will first think of the development of computer technology, because of the development of computer technology, people can feel, but, in contrast, the development of LAN technology, from the first generation multiplied by the second generation of hubs and switches, bandwidth and third-tier switching time, and then the development of the third generation of intelligent network era, ordinary netizens do not seem to think what changes, because the network is the information age infrastructure, is carried out behind the scenes, so ordinary users do not have much understanding, only feel the network speed, Networks can provide more services, in fact, all of which can not be separated from the continued growth of network technology.